1. Technical Field
The present invention relates to a liquid ejecting apparatus and a flying curve detecting method, and more particularly, to an ink jet printing apparatus and a method of detecting a flying curve of dots ejected by the ink jet printing apparatus capable of ejecting ink as a liquid.
2. Related Art
As a liquid ejecting apparatus ejecting a liquid on an ejecting target medium, there is known an ink jet printing apparatus capable of performing printing on a printing medium (ejecting target medium) such as a paper sheet or a print sheet by ejecting ink as a liquid. An ink jet printing head has a nozzle row in which nozzles ejecting ink are arranged and is disposed in the ink jet printing apparatus so that an arrangement direction of the nozzles intersects a main scanning direction.
The ink jet printing apparatus performs one-pass printing by moving the ink jet printing head in the main scanning direction with respect to the printing medium. In the one-pass printing, the ink jet printing head moves in the main scanning direction while ejecting the ink so as to eject the ink continuously from the nozzles arranged in the arrangement direction in the main scanning direction. In addition, by moving the printing medium in a sub-scanning direction intersecting the main scanning direction, the printing is realized on the entire surface of the printing medium.
In such an ink jet printing apparatus, a problem may arise in that ink droplets ejected from the nozzles curvedly fly due to the ink saturated in the vicinities of the nozzles and thus the ink droplets are landed to a position deviated from the original landing position of the printing medium. In order to detect such a flying curve, there was suggested an apparatus capable of detecting the flying curve on the basis of whether a predetermined test pattern is formed with a predetermined shape by forming the test pattern on the printing medium (for example, see JP-A-2007-21968).
Specifically, the ink jet printing apparatus prints a so-called solid test pattern on a printing medium by continuously ejecting ink in the main scanning direction from the respective nozzles. At this time, when a flying curve occurs in one nozzle, dots formed by the corresponding nozzle may be formed at positions deviated from the original landing positions and thus some dots become void in a ground portion (the surface of the printing medium). By viewing the ground portion, it is possible to detect the flying curve.
However, since the ink droplets are ejected with a high density, a problem may arise in that it is difficult to view the deviated ink droplets easily even in a case where the ink droplets curvedly fly and land at the deviated positions.
Alternatively, the flying curve can be detected by reading the test pattern by an optical unit, for example, to determine whether the test pattern is formed with a predetermined shape. However, a problem with cost may arise in that an optical unit, a member, or an apparatus has to be further provided to detect the flying curve.
Moreover, such a problem may occur not only in the ink jet printing head but a liquid ejecting apparatus ejecting a liquid other than ink.